Art of molding pottery



UNITED STATES PATENT Orrron.

GEORGE LIGOFVSKY, OF CINCINNATI, OHIO.

ART OF MOLDING POTTERY.

SFECEFICATION forming part of Letters Patent No, 318,917, dated May 26, 1885.

Application filed August 29, 1884.

To all whom, it may concern:

Be it known that I, GEORGE LIGoWsKY, of Cincinnati, county of Hamilton, and State of Ohio, have invented certain new and useful Improvements in the Art of Molding Pottery, of which the following is a specification.

Pottery molded by the usual process is de faced by seams at the line of junction of the different sections of the mold, which mar the effect and reduce the value of all pottery, and especially of art-pottery. llIuch time and skill are expended in reducing these seams, which cannot be wholly obliterated.

My invention has for its object the production of pottery in which all or a part of these seams are done-away with; and I accomplish this as follows: In a mold made in sections in the usual way I cast an intermediate or last pattern of sulphur or other frangible material which will form a hard deposit upon the surface, making athin shell, or of rubber or other elastic material, in which case it will be cast around a suitable core. WVhen the mold is taken off, it leaves a hollow pattern, which is the reverse of the mold, and has the seams which would ordinarily appear upon the pottery. These seams are then cut away and made invisible, which is readily done, the material oi'which the secondary pattern is made being easily worked. Upon the pattern so prepared I cast another and seamless mold. The pattern, if of frangible material, is broken away; but if of elastic material the core is removed and the elastic jacket is readily taken out. The casting is then made in the secondary or working mold.

In order that the mold may deliver freely when the design is in relief or the mold underout, I use clay, which contracts considerably as it hardens, thus drawing away from the depressions or undershot portions of the mold.

In this way seamless pottery may be obtained when the shrinkage is equal or a little (N0 specimens.)

more than equal to the difference between the greatest internal diameter of the mold and its diameter at the point of delivery.- When the difference in diameter of the proposed casting at different points is too great to allow of its being cast in a solid mold, as above described, the same process may be used to reduce the number of seams.

It is often possible to make a horizontal seam coincide with the design in such a way that the seam does notinjure the appearance of the product; but this can rarely, if ever, be done with vertical seams. By taking advantage of this fact and by the use of the abovedescribed process most, if not all, desirable forms of pottery whose proportions are such that they cannot be cast from an integral mold can be produced with but one seam, which may be horizontal and correspond with an ofi' set in the design in such a manner as to preserve the symmetry of the product.

This process will be found especially advan tageous in the manufacture of art-pottery with designs in relief.

I claim- 1. The above-described process of molding pottery, consisting in casting from the original mold an intermediate or last pattern of readily-removable material, reducing the seams upon said intermediate pattern, casting a working mold thereon, and molding therefrom.

2. An intermediate or last pattern composed of an integral shell of cohesive frangible material, substantially as and for the purposes described.

3. A waste or last pattern composed of a thin integral shell of sulphur, substantially as and for the purpose specified.

GEORGE LIGOWSKY. Witnesses:

S. S. CARPENTER, Gno. B. PARKINSON. 

